Globoside is a neutral glycosphingolipid in human erythrocytes and has blood-group-P-antigen activity [4]. The enzyme requires a divalent cation for activity, with Mn2+ required for maximal activity [3]. UDP-GalNAc is the only sugar donor that is used efficiently by the enzyme: UDP-Gal and UDP-GlcNAc result in very low enzyme activity [3]. Lactosylceramide, globoside and gangliosides GM3 and GD3 are not substrates [4]. For explanation of the superscripted ’3′ in the systematic name, see GL-5.3.4.